Sazbon et al. describe a method of this sort for range estimation in “Qualitative Real-Time Range Extraction for Preplanned Scene Partitioning Using Laser Beam Coding,” Pattern Recognition Letters 26 (2005), pages 1772-1781, which is incorporated herein by reference. A phase-only filter codes the laser beam into M different diffraction patterns, corresponding to M different range segments in the workspace. Thus, each plane in the illuminated scene is irradiated with the pattern corresponding to the range of the plane from the light source. A common camera can be used to capture images of the scene, which may be processed to determine the ranges of objects in the scene. The authors describe an iterative procedure for designing the phase-only filter based on the Gerchberg-Saxton algorithm.
US Patent Publication No. 2011/0158508 to Shpunt et al. discloses a method for mapping which uses a diffractive optical element and includes projecting onto an object a pattern of multiple spots having respective positions and shapes, such that the positions of the spots in the pattern are uncorrelated, while the shapes share a common characteristic. An image of the spots on the object is captured and processed so as to derive a three-dimensional (3D) map of the object.
U.S. Pat. Nos. 8,090,194, 8,208,719 and 8,538,166 to Gordon et al. and International Publication No. WO2008062407 also to Gordon et al. disclose various aspects of structured light projection and imaging as well features, hardware and algorithms used in structured light projection and imaging.